Well, if Natsu joins Zeref in a fanfiction, it might start with Natsu being forced into it somehow. Maybe Zeref has some sort of leverage over Natsu, like threatening his friends. Natsu would then have to figure out how to work with Zeref while still holding onto his own values. Their relationship could be very strained at first. But as time goes on, they could start to understand each other better and even develop a sort of begrudging respect for one another.
In a Natsu joins Zeref fanfiction, one possibility is that Natsu could initially be conflicted. He has always seen Zeref as an enemy, but perhaps there's a common goal they discover. For example, they might find out about a greater evil that threatens the entire magical world. Natsu's fiery nature could be used in a new way when combined with Zeref's dark magic. This could lead to a very different power dynamic compared to what we see in the original Fairy Tail story.
A Natsu joins Zeref fanfiction could be really interesting. Natsu is all about life and friendship, while Zeref is associated with death and destruction. Their union could be a way to explore the balance between these two extremes. It could also lead to some great character development for both of them. Natsu might learn more about the dark side of magic and Zeref could be reminded of the good in the world through Natsu. And there could be a lot of action as they face off against foes who are both afraid and intrigued by their new alliance.
Well, it could be chaos. Zeref's dark powers would likely disrupt the harmony of Fairy Tail at first. His presence might cause a lot of suspicion and fear among the guild members.
If Natsu and Zeref join Fairy Tail in fanfiction, it would change the dynamic of the guild completely. The other members would have mixed reactions. Some might be distrustful of Zeref due to his past actions. However, as time passes, they could see the good in him. Natsu and Zeref together could attract a lot of attention from outside forces. Enemies might target Fairy Tail more because of their combined power. But also, they could inspire the guild to become even stronger, with everyone striving to keep up with their new powerful comrades.
Most of the Fairy Tail members would not take it well. Happy, Natsu's closest friend, would be extremely confused and sad. He'd follow Natsu around, trying to get him to come back to the guild. Makarov, the guild master, would see it as a huge threat to the guild's safety. He might send some of the stronger members to keep an eye on Natsu and Zeref. And the younger members like Wendy would look up to Natsu so much that they'd be very disappointed and scared for him, thinking that he's making a big mistake by joining Zeref.
He might lose his friends at Fairy Tail. Since Fairy Tail is all about friendship and light, joining a dark guild would put him at odds with his former comrades.
In this fanfiction scenario, one possible thing that could happen is that Natsu's determination to defeat Zeref might be put to the ultimate test. Natsu has always been a fighter with a strong will, and facing Zeref, he would have to dig deep. Zeref, on the other hand, being extremely powerful, might initially have the upper hand. But Natsu could tap into some hidden power, perhaps related to his dragon slayer magic in a new and unexpected way. Maybe he would get some kind of emotional boost from his friends in Fairy Tail who are watching, which gives him the edge he needs to turn the battle around.
Another idea for this fanfiction could be that they were both students at a very old and secret magic academy in the past. Zeref was an outcast because of her dark magic, but Natsu didn't care. He befriended her, and together they explored the secrets of the academy and the magic within it. However, their friendship was soon tested when the academy's elders discovered Zeref's true nature.
Well, it depends on the specific fanfiction. Some fanfictions do make Zeref and Natsu brothers. This can create some really cool plot twists. For instance, it could change how Natsu views his powers if he discovers he's related to Zeref. And it might also make Zeref more protective or possessive of Natsu in a different way than in the original story. It's a concept that allows for a lot of creativity in the fanfiction world.
A lot of these fanfictions also have a theme of redemption. Fem Zeref might be portrayed as a character seeking redemption for past actions, and Natsu could be the catalyst for that change. It's a way to give a new perspective to Zeref's character. Additionally, themes of friendship or unrequited love are also common. The relationship between Natsu and Fem Zeref can be explored in a platonic or romantic way, and often there are misunderstandings and moments of self - discovery related to these feelings.
Well, one possible plot could be that Zeref kidnaps Natsu in an attempt to use his power for some dark purpose. Maybe he wants to turn Natsu into a weapon against Fairy Tail. Zeref might believe that Natsu's unique dragon - slayer magic can be harnessed in a way that no one else's can.
Well, perhaps Zeref kidnaps Natsu because he sees Natsu as a key to some grand plan. Maybe he wants to use Natsu's power for his own dark purposes. For example, Zeref might think Natsu's unique magic can help him break some sort of ancient curse or gain access to a powerful magic source.